Question: Tiffany was assigned problems 31 through 54 for homework tonight. If Tiffany did all of the problems she was assigned, how many problems did she do?
Instead of counting problems 31 through 54, we can subtract 30 from each number so we instead consider problems 1 through 24. We see that Tiffany did 24 problems. Notice that she did 24 and not 23 problems.